Sunanda Pushkar, the wife of the Indian government minister and former high-ranking UN official Shashi Tharoor, died an "unnatural, sudden death", according to a doctor who examined her body after it was found in a Delhi hotel room on Friday.

"We can say that it is a case of unnatural sudden death. There were certain injury marks on the body, but we can't divulge details at this point," said Sudhir Kumar Gupta, one of three forensic scientists who carried out her autopsy and was quoted in the Press Trust of India on Saturday.

The claims that she was injured contradict earlier police claims. Indian police continue to investigate Pushkar's death, which came after allegations that her husband was having an affair with a Pakistani journalist.

The death of Pushkar, 52, is the latest twist in a scandal that has gripped Indian politics and the media and has engulfed the ministerial career of Tharoor, a former under-secretary-general at the UN under Kofi Annan who ran for the top job in 2007, only to see it go to Ban Ki-moon.

Pushkar's body was found in a suite at the Leela hotel. She had made a series of confused tweets and public statements over several days in response to media reports that she had been angry about text messages and tweets purported to have been exchanged between her husband and Mehr Tarar, a Pakistani journalist.

Pushkar had posted her messages on the timeline of Tharoor, who has two million followers and is known as "Minister Twitter" for his extensive use of social media. One message allegedly sent directly to Tharoor from the journalist declared: "I love you, Shashi Tharoor. And I go while in love with you, irrevocably, irreversibly."

Pushkar said she had gone into her husband's Twitter account and put out private messages that she said Tarar had sent to her husband over Blackberry Messenger. In a series of interviews and statements to the Economic Times and Indian Express, she claimed that the journalist had stalked her husband and that the two were having a "rip-roaring affair".

She backtracked a day later to issue a joint statement on Thursday with her husband that the release of the messages had been "unauthorised", insisting that the couple were happily married and intended to stay that way.

Tarar denied she was having an affair with the Indian minister and said she would sue Pushkar for defamation.

The first statement from the forensic team came after the London-born Tharoor was taken to hospital complaining of chest pains immediately after his wife's death.

In a separate statement directly contradicting Gupta, Tharoor's personal assistant, Abhinav Kumar, told reporters outside the luxury hotel: "She was lying in bed. There were no signs of any foul play or any struggle ... She had no sign of poisoning or anything."

Tharoor's aides said the couple had checked into the Leela because of renovation work at his Delhi bungalow. He left the hotel room on Friday to attend a session of the ruling Congress party in the capital, but returned late in the day to find the door locked. It was forced open to reveal the body of his wife.

Tharoor, 57, married Pushkar in 2010, a third marriage for each of them. Earlier that year he had been forced to resign from his first ministerial job after accusations linking him to a company bidding in the lucrative Indian Premier League for a cricket team from his home state of Kerala. Pushkar had a stake in the company at the time.

Tarar said she was shocked by the death. "Oh my God," she tweeted. "This is too awful for words. So tragic I don't know what to say. Rest in peace."

Tharoor has stirred controversy in the past by posting a message that he would travel "cattle class" following reports about his lavish lifestyle.

The full autopsy report is scheduled to be released in the next few days.